Influence of mechanical strain on essential characteristics of GMR structures

Giant magnetoresistance (GMR) of Co and Fe-Co based structures with Cu and Au spacers were e-beam evaporated onto Si wafers. The thickness of layers was obtained from the simulation of X-ray reflectivity spectra. The GMR ratio was between 3.3 and 5.6 %. The effect of strain upon samples was studied in a bending configuration. The different dependences of coercivity (H_c) vs. strain were found. For example, for sample with Co(5)/Au(2.2)/Co(2) core structure (where numbers denote thickness in nm) H_c increases with increasing compressive stress, whereas for sample with Co(0.5)/Cu(3)/Co(5) core structure it increases with tensile stress. The relative change of GMR ratio vs. loading in the strain interval plusmn 280times10^-6 is 1-2 % near to the point of inflection of GMR vs. H curve (3.6 kA/m) for the second sample. The structures can be further optimized and applied in sensors of mechanical quantities